Technical Abstract:
Lysine, threonine and methionine are synthesized from aspartate and are essential amino acids required in the diets of non-ruminant animals. Major crops, such as corn, soybean and rice, are low in one or more of these amino acids. Currently these amino acids are added as supplements to animal feed to provide animals with their amino acid requirements for optimal growth. The cost of these supplements are a direct expense for farmers and are passed on to the consumer. Prospects of manipulating this pathway to increase the content of lysine, threonine and methionine in plants has generated a great deal of interest. This review describes recent discoveries and advances in understanding the biochemistry and molecular biology of the enzymes and genes in this pathway. This work is of importance to plant biochemists, geneticists and molecular biologists interested in studying and genetically engineering plants to alter amino acid production.